Integrating signaling and transcriptional control in neural crest specification

描述（由申请人提供）：神经嵴是一种多能胚胎细胞群，在颅面发育中起着核心作用，产生了面部的大部分骨骼元素。神经嵴发育异常是导致颅面畸形和出生缺陷的主要原因。颅神经嵴的特化是一个复杂的过程，需要信号分子、受体和转录调节因子之间的相互作用。特别是，Wnt信号通路已被证明是神经嵴发育的主要驱动力。从不同的模式生物获得的数据表明，抑制Wnt活性废除了神经嵴基因的表达，而过度激活的神经嵴基因则可以抑制神经嵴基因的表达。 典型的Wnt途径组分导致神经嵴命运的扩张。然而，Wnt信号转导增强神经嵴身份的分子机制仍然难以捉摸。在这个应用程序中，我将研究Wnt通路如何驱动赋予神经嵴独特功能的基因的激活。我假设Wnt效应基因与祖细胞中存在的转录调节因子合作，触发神经嵴特化程序。这一假设得到了我的初步实验的支持，这表明转录调节因子Axud1在Wnt信号传导和神经嵴特化之间起着以前未被识别的联系。在这里，我将通过使用loss来确定Axud1在规范中的作用 的功能的方法在鸡胚胎，并仔细检查它是如何激活的Wnt神经嵴祖细胞。随后，我将研究Wnt通路的成员如何与神经嵴规范的其他驱动程序相互作用，以激活下游靶点在顺式调节水平的表达。拟议的实验结果将阐明信号通路如何与转录机制相结合，以允许新生神经嵴细胞的出现。扩展控制头神经嵴发育的分子程序的知识将产生对遗传学的新见解。 颅面疾病的基础，并可能影响治疗和再生应用。

DESCRIPTION (provided by applicant): The neural crest is a multipotent embryonic cell population that plays a central role in craniofacial development, giving rise to most of the skeletal elements of the face. Abnormal neural crest development is the leading cause of craniofacial malformations and birth defects. Specification of the cranial neural crest is a complex process that requires interplay between signaling molecules, receptors, and transcriptional regulators. In particular, the Wnt signaling pathway has been shown to be a major driver of neural crest development. Data obtained from different model organisms show that inhibition of Wnt activity abrogates expression of neural crest genes, while overactivation of canonical Wnt pathway components results in expansion of neural crest fates. However, the molecular mechanism through which Wnt signaling elicits neural crest identity remains elusive. In this application, I will investigate how the Wnt-pathway drives activation of the genes that endow the neural crest with its unique features. I hypothesize that Wnt-effector genes cooperate with transcriptional regulators present in progenitors to trigger the neural crest specification program. This hypothesis is supported by my preliminary experiments, which suggests that transcriptional regulator Axud1 acts as a previously unidentified link between Wnt signaling and neural crest specification. Here, I will determine the role of Axud1 in specification by using loss of function approaches in the chicken embryo, and scrutinize how it is activated by Wnts in neural crest progenitors. Subsequently, I will investigate how members of the Wnt pathway interact with other drivers of neural crest specification to activate the expression of downstream targets at the cis-regulatory level. The results of the proposed experiments will shed light on how signaling pathways are integrated with the transcriptional machinery to allow for the emergence of nascent neural crest cells. Expanding the knowledge of molecular programs controlling the development of the cephalic neural crest will yield novel insights into the genetic basis of craniofacial disease and can impact therapeutic and regenerative applications.